Self-contained breathing apparatuses that are used, for example, by firefighters include a carrying frame strapped to the body with an attached breathing regulator. Breathing hoses extend from the regulator to a mouthpiece which the firefighter carries in his mouth when in use. The breathing air is supplied by a compressed-air tank with a structural volume of approximately 6 liters. To enable the tank to hold a sufficient volume, the air in the tank is compressed to approximately 300 bar.
The connection that supplies breathing-air from the tank to the regulator can be disconnected. In this way, the air tank can be refilled on the emergency vehicle without any potential danger. Once filled, the tank is attached to the carrying frame and re-connected to the regulator so as to allow the flow of air from the tank. This connection of the tank to the regulator should happen relatively quickly in order to avoid any loss of time. In addition, the connection must be easy to make. If complicated handling were required it could present a potential danger.
The compressed-air tank has a separate hand valve so that connecting the compressed-air tank both to the pump and also to the regulator can be performed without pressure. This significantly simplifies the necessary couplings. However, a situation in which inadvertent actuation of the tank valve leads to an impermissible build-up of pressure in parts of the coupling device preferably should be prevented because otherwise a later connection may be impossible. Moreover, a dangerous air flow should not be produced when the tank valve is opened.
Additional issues relating to the connection point include preventing the penetration of foreign matter when the coupling is disconnected and preventing a build-up of pressure caused by an inadvertently opened tank valve.